| Autor: |
Kumar, Ajay, Singh, Shashwat K., Mitra, S., Priestley, K. F., Dayal, Shankar |
| Předmět: |
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| Zdroj: |
Geophysical Journal International; Feb2017, Vol. 208 Issue 2, p992-1008, 17p |
| Abstrakt: |
The 2015 Gorkha earthquake (Mw 7.8) occurred by thrust faulting on a ~150 km long and ~70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the main-shock rupture and source mechanism of aftershocks. The main-shock initiated ~80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards along ~117° azimuth for a duration of ~70 s, with varying rupture velocity on a heterogeneous fault surface. The main-shock has been modelled using four subevents, propagating from west-to-east. The first subevent (0-20 s) ruptured at a velocity of ~3.5 km s-1 on a ~6°N dipping flat segment of the MHT with thrust motion. The second subevent (20-35 s) ruptured a~18°Wdipping lateral ramp on theMHTin oblique thrust motion. The rupture velocity dropped from 3.5 km s-1 to 2.5 km s-1, as a result of updip propagation of the rupture. The third subevent (35-50 s) ruptured a ~7°N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth subevent (50-70 s) occurred by left-lateral strikeslip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the main-shock rupture. Eastward stress build-up following the mainshock resulted in the largest aftershock (Mw 7.3), which occurred on the MHT, immediately east of the main-shock rupture. Source mechanisms of moderate aftershocks reveal stress adjustment at the edges of the main-shock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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